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Fluctuation dynamos are generic to astrophysical systems. The only analytical model of the fluctuation dynamo is Kazantsev model which assumes a delta-correlated in time velocity field. We derive a generalized model of fluctuation dynamo…

Plasma Physics · Physics 2014-08-25 Pallavi Bhat , Kandaswamy Subramanian

Fluctuation dynamos occur in most turbulent plasmas in astrophysics and are the prime candidates for amplifying and maintaining cosmic magnetic fields. A few analytical models exist to describe their behaviour but they are based on…

Astrophysics of Galaxies · Physics 2023-07-03 Yann Carteret , Dominik Schleicher , Jennifer Schober

The small-scale dynamo is typically studied by assuming that the correlation time of the velocity field is zero. Some authors have used a smooth renovating flow model to study how the properties of the dynamo are affected by the correlation…

Astrophysics of Galaxies · Physics 2024-05-01 Kishore Gopalakrishnan , Nishant K Singh

Hydromagnetic dynamo theory provides the prevailing theoretical description for the origin of magnetic fields in the universe. Here we consider the problem of kinematic, small-scale dynamo action driven by a random, incompressible,…

Plasma Physics · Physics 2011-03-10 Joanne Mason , Leonid Malyshkin , Stanislav Boldyrev , Fausto Cattaneo

Most of the theoretical results on the kinematic amplification of small-scale magnetic fluctuations by turbulence have been confined to the model of white-noise-like advecting turbulent velocity field. In this work, the statistics of the…

Astrophysics · Physics 2009-10-31 Alexander Schekochihin , Russell Kulsrud

We consider the kinematic fluctuation dynamo problem in a flow that is random, white-in-time, with both solenoidal and potential components. This model is a generalization of the well-studied Kazantsev model. If both the solenoidal and…

Fluid Dynamics · Physics 2019-03-08 Marco Martins Afonso , Dhrubaditya Mitra , Dario Vincenzi

We consider a natural generalization of the Kazantsev-Kraichnan model for small-scale turbulent dynamo. This generalization takes account of statistical time asymmetry of a turbulent flow, and, thus, allows to describe velocity fields with…

Fluid Dynamics · Physics 2023-10-26 A. V. Kopyev , A. M. Kiselev , A. S. Il'yn , V. A. Sirota , K. P. Zybin

We present a theory of large-scale dynamo action in a turbulent flow that has stochastic, zero-mean fluctuations of the $\alpha$ parameter. Particularly interesting is the possibility of the growth of the mean magnetic field due to Moffatt…

Astrophysics of Galaxies · Physics 2016-06-29 Nishant K. Singh

We study the Lagrangian mechanism of the fluctuation dynamo at zero Prandtl number and infinite magnetic Reynolds number, in the Kazantsev-Kraichnan model of white-noise advection. With a rough velocity field corresponding to a turbulent…

Plasma Physics · Physics 2011-03-07 Gregory L. Eyink

The presence of magnetic fields in many astrophysical objects is due to dynamo action, whereby a part of the kinetic energy is converted into magnetic energy. A turbulent dynamo that produces magnetic field structures on the same scale as…

Astrophysics of Galaxies · Physics 2020-03-19 Amit Seta , Paul J. Bushby , Anvar Shukurov , Toby S. Wood

Magnetic fluctuations with a zero mean field in a random flow with a finite correlation time and a small yet finite magnetic diffusion are studied. Equation for the second-order correlation function of a magnetic field is derived. This…

Astrophysics · Physics 2009-11-07 N. Kleeorin , I. Rogachevskii , D. Sokoloff

This paper is a detailed report on a programme of simulations used to settle a long-standing issue in the dynamo theory and demonstrate that the fluctuation dynamo exists in the limit of large magnetic Reynolds number Rm>>1 and small…

The Landau-Lifshitz fluctuating hydrodynamics is used to study the statistical properties of the linearized Kolmogorov flow. The relative simplicity of this flow allows a detailed analysis of the fluctuation spectrum from near equilibrium…

Condensed Matter · Physics 2009-11-07 I. Bena , M. Malek Mansour , F. Baras

We investigate the Lagrangian mechanism of the kinematic ``fluctuation'' magnetic dynamo in turbulent plasma flow at small magnetic Prandtl numbers. The combined effect of turbulent advection and plasma resistivity is to carry infinitely…

Plasma Physics · Physics 2015-05-13 Gregory L. Eyink , Antonio F. Neto

We investigate the structure of magnetic field amplified by turbulent velocity fluctuations, in the framework of the kinematic Kazantsev-Kraichnan model. We consider Kolmogorov distribution of velocity fluctuations, and assume that both…

Astrophysics · Physics 2010-01-15 Leonid Malyshkin , Stanislav Boldyrev

We consider the kinematic stage of evolution of magnetic field advected by turbulent hydrodynamic flow. We use a generalization of the Kazantsev-Kraichnan model to investigate time irreversible flows. In the viscous range of scales, the…

Fluid Dynamics · Physics 2023-10-26 A. V. Kopyev , A. S. Il'yn , V. A. Sirota , K. P. Zybin

We study magnetic field evolution in flows with fluctuating in time governing parameters in electrically conducting fluid. We use a standard mean-field approach to derive equations for large-scale magnetic field for the fluctuating ABC-flow…

Astrophysics · Physics 2009-11-13 N. Kleeorin , I. Rogachevskii , D. Sokoloff , D. Tomin

We study the dynamo instability for a Kazantsev-Kraichnan flow with three velocity components that depends only on two-dimensions u = (u(x, y, t), v(x, y, t), w(x, y, t)) often referred to as 2.5 dimensional (2.5D) flow. Within the…

Fluid Dynamics · Physics 2016-11-03 K. Seshasayanan , A. Alexakis

We study how fluctuations in fluid dynamic fields can be dissipated or amplified within the characteristic spatio-temporal structure of a heavy ion collision. The initial conditions for a fluid dynamic evolution of heavy ion collisions may…

Nuclear Theory · Physics 2012-08-20 Stefan Floerchinger , Urs Achim Wiedemann

The influence of fluctuating conductivity on the coefficients known from the mean-field electrodynamics is considered. If the conductivity fluctuations are assumed as uncorrelated with the turbulent velocity field then only the effective…

Plasma Physics · Physics 2020-07-15 G. Rüdiger , M. Küker , P. J. Käpylä
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